Extreme events: Past and future changes in the attributes of extreme rainfall and the dynamics of their driving processes

Expanded Title:

The purpose of this study was to investigate changes in the characteristics of extreme rainfall by establishing relationships between existing station data and the daily synoptic states. To achieve this aim, the main objectives set entailed producing rainfall station data set that had been quality controlled according to international standards so that these data could be confidently used in identifying key synoptic process that resulted in extreme rainfall based on the cleaned station data and atmospheric circulation fields and trends in these. The methodology entailed application of station data quality control to station data obtained from the CCWR, ARC and SAWS. Despite errors and conflicts identified among the datasets, a quality controlled station data set that could be used in the rest of the study was produced. The regionally specific characteristics of extreme rainfall in South Africa were also identified. Findings were that: Summer recorded the highest occurrence of extreme rainfall in all regions with the exception of the South Western Cape and South Coast regions. Based on the results, it was recommended that extreme rainfall regimes should be identified as opposed to general rainfall regimes, an event-based classification procedure of extreme rainfall synoptic circulation modes should be used, a climate change study on projected changes in the characteristics of extreme rainfall CODEX framework should be undertaken and a downscale to station scale the new CMIP 5 GCM data must be done to compare with contemporary station data.